  <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>表格全选</title>
    <style>
        table{
            border: 1px solid;
            width: 500px;
            margin-left: 30%;
        }

        td,th{
            text-align: center;
            border: 1px solid;
        }
        div{
            margin-top: 10px;
            margin-left: 30%;
        }

        .out{
            background-color: white;
        }
        .over{
            background-color: pink;
        }
    </style>

    <script>
        /*
          分析：
              1.全选：
                  * 获取所有的checkbox
                  * 遍历cb，设置每一个cb的状态为选中  checked

         */


        //1.在页面加载完后绑定事件
        window.onload = function(){
            document.getElementById("selectAll").onclick = function(){
                //全选
                //1.获取所有的checkbox
                var cbs = document.getElementsByName("cb");
                for (var i = 0; i < cbs.length; i++) {
                    //3.设置每一个cb的状态为选中  checked
                    cbs[i].checked = true;
                }
            }

            document.getElementById("unSelectAll").onclick = function(){
                //全不选
                //1.获取所有的checkbox
                var cbs = document.getElementsByName("cb");
                //2.遍历
                for (var i = 0; i < cbs.length; i++) {
                    cbs[i].checked = false;
                }
            }

            document.getElementById("selectRev").onclick = function(){
                //反选
                //1.获取所有的checkbox
                var cbs = document.getElementsByName("cb");
                //2.遍历
                for (var i = 0; i < cbs.length; i++) {
                    //3.设置每一个cb的状态为相反
                    cbs[i].checked = !cbs[i].checked;
                }
            }

            document.getElementById("firstCb").onclick = function(){
                //第一个cb点击
                //1.获取所有的checkbox
                var cbs = document.getElementsByName("cb");
                //获取第一个cb
                //2.遍历
                for (var i = 0; i < cbs.length; i++) {
                    //3.设置每一个cb的状态和第一个cb的状态一样
                    cbs[i].checked =  this.checked;
                }
            }
            //给所有tr绑定鼠标移到元素之上和移出元素事件
            var trs = document.getElementsByTagName("tr");
            //2.遍历
            for (var i = 0; i < trs.length; i++) {
                //移到元素之上
                trs[i].onmouseover = function(){
                    this.className = "over";
                }

                //移出元素
                trs[i].onmouseout = function(){
                    this.className = "out";
                }

            }

        }



    </script>

</head>
<body>

<table>
    <caption>学生信息表</caption>
    <tr>
        <th><input type="checkbox" name="cb" id="firstCb"></th>
        <th>编号</th>
        <th>姓名</th>
        <th>性别</th>
        <th>操作</th>
    </tr>

    <tr>
        <td><input type="checkbox"  name="cb" ></td>
        <td>1</td>
        <td>令狐冲</td>
        <td>男</td>
        <td><a href="javascript:void(0);">删除</a></td>
    </tr>

    <tr>
        <td><input type="checkbox"  name="cb" ></td>
        <td>2</td>
        <td>任我行</td>
        <td>男</td>
        <td><a href="javascript:void(0);">删除</a></td>
    </tr>

    <tr>
        <td><input type="checkbox"  name="cb" ></td>
        <td>3</td>
        <td>岳不群</td>
        <td>?</td>
        <td><a href="javascript:void(0);">删除</a></td>
    </tr>

</table>
<div>
    <input type="button" id="selectAll" value="全选">
    <input type="button" id="unSelectAll" value="全不选">
    <input type="button" id="selectRev" value="反选">
</div>
</body>
</html>